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https://www.timeout.com/travel/coolest-neighbourhoods-in-the-world-2025
Two things I noticed is how many places have hideous overhead wires,
and how much signage is in English.
On Sat, 27 Sep 2025 09:10:29 -0700, john larkin <jl@glen--canyon.com>
wrote:
https://www.timeout.com/travel/coolest-neighbourhoods-in-the-world-2025
Two things I noticed is how many places have hideous overhead wires,
and how much signage is in English.
I lived in Berlin for some years in a delightful Kietz very similar to
number 1 on this list: antiquarian booksellers on every street. Some
really fascinating titles got published pre-1900; stuff that would
never see the light of day now.
On Sun, 28 Sep 2025 09:04:52 +0100, Cursitor Doom <cd@notformail.com>
wrote:
On Sat, 27 Sep 2025 09:10:29 -0700, john larkin <jl@glen--canyon.com> >>wrote:
https://www.timeout.com/travel/coolest-neighbourhoods-in-the-world-2025
Two things I noticed is how many places have hideous overhead wires,
and how much signage is in English.
I lived in Berlin for some years in a delightful Kietz very similar to >>number 1 on this list: antiquarian booksellers on every street. Some
really fascinating titles got published pre-1900; stuff that would
never see the light of day now.
I modestly note that my little niche is #35 on the list. My little lab
is a two minute walk from GPS, which is an authentic old dive bar.
I asked the bar lady "Do you have any good rum, like Ron Zacapa?" and
she said "This ain't that kind of joint, honey."
The Glen Park library is were they busted the Silk Road guy. A few
blocks away is (or emphatically was) the first dynamite factory in the
USA.
On Sun, 28 Sep 2025 08:16:10 -0700, john larkin <jl@glen--canyon.com>
wrote:
On Sun, 28 Sep 2025 09:04:52 +0100, Cursitor Doom <cd@notformail.com> >>wrote:
On Sat, 27 Sep 2025 09:10:29 -0700, john larkin <jl@glen--canyon.com> >>>wrote:
Two things I noticed is how many places have hideous overhead wires, >>>>and how much signage is in English.https://www.timeout.com/travel/coolest-neighbourhoods-in-the-world-2025 >>>>
I lived in Berlin for some years in a delightful Kietz very similar to >>>number 1 on this list: antiquarian booksellers on every street. Some >>>really fascinating titles got published pre-1900; stuff that would
never see the light of day now.
I modestly note that my little niche is #35 on the list. My little lab
is a two minute walk from GPS, which is an authentic old dive bar.
I've heard this term 'dive bar' before in popular songs. What exactly
is that? I'm guessing some seedy joint where felonious types play
pool?
I asked the bar lady "Do you have any good rum, like Ron Zacapa?" and
she said "This ain't that kind of joint, honey."
Classic Americana. :-D
The Glen Park library is were they busted the Silk Road guy. A few
blocks away is (or emphatically was) the first dynamite factory in the
USA.
Oh dear! Go *bang* did it?
Very quiet here today. Not even any of the regular trolls around.
On Sun, 28 Sep 2025 17:38:40 +0100, Cursitor Doom <cd@notformail.com>
wrote:
On Sun, 28 Sep 2025 08:16:10 -0700, john larkin <jl@glen--canyon.com> >>wrote:
On Sun, 28 Sep 2025 09:04:52 +0100, Cursitor Doom <cd@notformail.com> >>>wrote:
On Sat, 27 Sep 2025 09:10:29 -0700, john larkin <jl@glen--canyon.com> >>>>wrote:
Two things I noticed is how many places have hideous overhead wires, >>>>>and how much signage is in English.https://www.timeout.com/travel/coolest-neighbourhoods-in-the-world-2025 >>>>>
I lived in Berlin for some years in a delightful Kietz very similar to >>>>number 1 on this list: antiquarian booksellers on every street. Some >>>>really fascinating titles got published pre-1900; stuff that would >>>>never see the light of day now.
I modestly note that my little niche is #35 on the list. My little lab
is a two minute walk from GPS, which is an authentic old dive bar.
I've heard this term 'dive bar' before in popular songs. What exactly
is that? I'm guessing some seedy joint where felonious types play
pool?
It's an old neighborhood bar that smells like an old neighborhood bar, >partonized by locals and worker-guys. It might have a pool table or a >fireplace. It has a few good but not fancy beers on tap.
The pizza place close by makes deliveries to your table at GPS. People
hate to let eating interfere with their drinking.
I asked the bar lady "Do you have any good rum, like Ron Zacapa?" and
she said "This ain't that kind of joint, honey."
Classic Americana. :-D
The Glen Park library is were they busted the Silk Road guy. A few
blocks away is (or emphatically was) the first dynamite factory in the >>>USA.
Oh dear! Go *bang* did it?
Yes. It lasted almost two years. They rebuilt it a couple miles to the
west, and that lasted two more.
https://www.dropbox.com/scl/fi/hi1j889kkn465fgpx5xgk/Glen_Canyon_Dynamite.jpg?rlkey=uq333s2okih26zgpicvcy7fb0&raw=1
Very quiet here today. Not even any of the regular trolls around.
Not much electronics here lately.
I need a small circuit to make +20 volts into -20 at maybe 400 mA.
There are lots of ways to do that.
https://www.timeout.com/travel/coolest-neighbourhoods-in-the-world-2025
Two things I noticed is how many places have hideous overhead wires,
and how much signage is in English.
On Sun, 28 Sep 2025 10:09:34 -0700, john larkin <jl@glen--canyon.com>
wrote:
On Sun, 28 Sep 2025 17:38:40 +0100, Cursitor Doom <cd@notformail.com> >>wrote:
On Sun, 28 Sep 2025 08:16:10 -0700, john larkin <jl@glen--canyon.com> >>>wrote:
On Sun, 28 Sep 2025 09:04:52 +0100, Cursitor Doom <cd@notformail.com> >>>>wrote:
On Sat, 27 Sep 2025 09:10:29 -0700, john larkin <jl@glen--canyon.com> >>>>>wrote:
Two things I noticed is how many places have hideous overhead wires, >>>>>>and how much signage is in English.https://www.timeout.com/travel/coolest-neighbourhoods-in-the-world-2025 >>>>>>
I lived in Berlin for some years in a delightful Kietz very similar to >>>>>number 1 on this list: antiquarian booksellers on every street. Some >>>>>really fascinating titles got published pre-1900; stuff that would >>>>>never see the light of day now.
I modestly note that my little niche is #35 on the list. My little lab >>>>is a two minute walk from GPS, which is an authentic old dive bar.
I've heard this term 'dive bar' before in popular songs. What exactly
is that? I'm guessing some seedy joint where felonious types play
pool?
It's an old neighborhood bar that smells like an old neighborhood bar, >>partonized by locals and worker-guys. It might have a pool table or a >>fireplace. It has a few good but not fancy beers on tap.
The pizza place close by makes deliveries to your table at GPS. People
hate to let eating interfere with their drinking.
I asked the bar lady "Do you have any good rum, like Ron Zacapa?" and >>>>she said "This ain't that kind of joint, honey."
Classic Americana. :-D
The Glen Park library is were they busted the Silk Road guy. A few >>>>blocks away is (or emphatically was) the first dynamite factory in the >>>>USA.
Oh dear! Go *bang* did it?
Yes. It lasted almost two years. They rebuilt it a couple miles to the >>west, and that lasted two more.
https://www.dropbox.com/scl/fi/hi1j889kkn465fgpx5xgk/Glen_Canyon_Dynamite.jpg?rlkey=uq333s2okih26zgpicvcy7fb0&raw=1
Very quiet here today. Not even any of the regular trolls around.
Not much electronics here lately.
I need a small circuit to make +20 volts into -20 at maybe 400 mA.
There are lots of ways to do that.
I need to make 250VDC @ 150mA from 240VAC Gotta be low noise. Any >suggestions?
On Sun, 28 Sep 2025 22:50:51 +0100, Cursitor Doom <cd@notformail.com>
wrote:
On Sun, 28 Sep 2025 10:09:34 -0700, john larkin <jl@glen--canyon.com> >>wrote:
On Sun, 28 Sep 2025 17:38:40 +0100, Cursitor Doom <cd@notformail.com> >>>wrote:
On Sun, 28 Sep 2025 08:16:10 -0700, john larkin <jl@glen--canyon.com> >>>>wrote:
On Sun, 28 Sep 2025 09:04:52 +0100, Cursitor Doom <cd@notformail.com> >>>>>wrote:
On Sat, 27 Sep 2025 09:10:29 -0700, john larkin <jl@glen--canyon.com> >>>>>>wrote:
Two things I noticed is how many places have hideous overhead wires, >>>>>>>and how much signage is in English.https://www.timeout.com/travel/coolest-neighbourhoods-in-the-world-2025 >>>>>>>
I lived in Berlin for some years in a delightful Kietz very similar to >>>>>>number 1 on this list: antiquarian booksellers on every street. Some >>>>>>really fascinating titles got published pre-1900; stuff that would >>>>>>never see the light of day now.
I modestly note that my little niche is #35 on the list. My little lab >>>>>is a two minute walk from GPS, which is an authentic old dive bar.
I've heard this term 'dive bar' before in popular songs. What exactly >>>>is that? I'm guessing some seedy joint where felonious types play
pool?
It's an old neighborhood bar that smells like an old neighborhood bar, >>>partonized by locals and worker-guys. It might have a pool table or a >>>fireplace. It has a few good but not fancy beers on tap.
The pizza place close by makes deliveries to your table at GPS. People >>>hate to let eating interfere with their drinking.
I asked the bar lady "Do you have any good rum, like Ron Zacapa?" and >>>>>she said "This ain't that kind of joint, honey."
Classic Americana. :-D
The Glen Park library is were they busted the Silk Road guy. A few >>>>>blocks away is (or emphatically was) the first dynamite factory in the >>>>>USA.
Oh dear! Go *bang* did it?
Yes. It lasted almost two years. They rebuilt it a couple miles to the >>>west, and that lasted two more.
https://www.dropbox.com/scl/fi/hi1j889kkn465fgpx5xgk/Glen_Canyon_Dynamite.jpg?rlkey=uq333s2okih26zgpicvcy7fb0&raw=1
Very quiet here today. Not even any of the regular trolls around.
Not much electronics here lately.
I need a small circuit to make +20 volts into -20 at maybe 400 mA.
There are lots of ways to do that.
I need to make 250VDC @ 150mA from 240VAC Gotta be low noise. Any >>suggestions?
There's not much in the way of commercial supplies in that range, and
nothing affordable.
A transformer+rectifier+filter should be OK.
What's the load going to be?
I got one of these
https://www.amazon.com/dp/B0F5GYY961?ref_=ppx_hzsearch_conn_dt_b_fed_asin_title_1&th=1
as a bench supply. Lower voltage versions are cheaper.
It's weird, in that the actual output voltage is very close to the
setpoint voltage, but it always displays 5 volts high.
John Larkin--- Synchronet 3.21a-Linux NewsLink 1.2
Highland Tech Glen Canyon Design Center
Lunatic Fringe Electronics
On Mon, 29 Sep 2025 09:42:39 -0700, john larkin <jl@glen--canyon.com>
wrote:
On Sun, 28 Sep 2025 22:50:51 +0100, Cursitor Doom <cd@notformail.com> >>wrote:
On Sun, 28 Sep 2025 10:09:34 -0700, john larkin <jl@glen--canyon.com> >>>wrote:
On Sun, 28 Sep 2025 17:38:40 +0100, Cursitor Doom <cd@notformail.com> >>>>wrote:
On Sun, 28 Sep 2025 08:16:10 -0700, john larkin <jl@glen--canyon.com> >>>>>wrote:
On Sun, 28 Sep 2025 09:04:52 +0100, Cursitor Doom <cd@notformail.com> >>>>>>wrote:
On Sat, 27 Sep 2025 09:10:29 -0700, john larkin <jl@glen--canyon.com> >>>>>>>wrote:
Two things I noticed is how many places have hideous overhead wires, >>>>>>>>and how much signage is in English.https://www.timeout.com/travel/coolest-neighbourhoods-in-the-world-2025 >>>>>>>>
I lived in Berlin for some years in a delightful Kietz very similar to >>>>>>>number 1 on this list: antiquarian booksellers on every street. Some >>>>>>>really fascinating titles got published pre-1900; stuff that would >>>>>>>never see the light of day now.
I modestly note that my little niche is #35 on the list. My little lab >>>>>>is a two minute walk from GPS, which is an authentic old dive bar.
I've heard this term 'dive bar' before in popular songs. What exactly >>>>>is that? I'm guessing some seedy joint where felonious types play >>>>>pool?
It's an old neighborhood bar that smells like an old neighborhood bar, >>>>partonized by locals and worker-guys. It might have a pool table or a >>>>fireplace. It has a few good but not fancy beers on tap.
The pizza place close by makes deliveries to your table at GPS. People >>>>hate to let eating interfere with their drinking.
I asked the bar lady "Do you have any good rum, like Ron Zacapa?" and >>>>>>she said "This ain't that kind of joint, honey."
Classic Americana. :-D
The Glen Park library is were they busted the Silk Road guy. A few >>>>>>blocks away is (or emphatically was) the first dynamite factory in the >>>>>>USA.
Oh dear! Go *bang* did it?
Yes. It lasted almost two years. They rebuilt it a couple miles to the >>>>west, and that lasted two more.
https://www.dropbox.com/scl/fi/hi1j889kkn465fgpx5xgk/Glen_Canyon_Dynamite.jpg?rlkey=uq333s2okih26zgpicvcy7fb0&raw=1
Very quiet here today. Not even any of the regular trolls around.
Not much electronics here lately.
I need a small circuit to make +20 volts into -20 at maybe 400 mA. >>>>There are lots of ways to do that.
I need to make 250VDC @ 150mA from 240VAC Gotta be low noise. Any >>>suggestions?
There's not much in the way of commercial supplies in that range, and >>nothing affordable.
I'd have thought *someone* must have such a supply, but as you say,
not much around.
A transformer+rectifier+filter should be OK.
What - you mean an isolation transformer or something with more
secodary turns?
What's the load going to be?
Plate voltages for 4x ECC83 toobs. They will run at above and below
250VDC, but it does change all sorts of parameters if they're tasked
to do that, so I'd prefer to stick to 250 for the sake of simplicity
and saves having to extrapolate from published data.
On Wed, 01 Oct 2025 14:19:14 +0100, Cursitor Doom <cd@notformail.com>
wrote:
On Mon, 29 Sep 2025 09:42:39 -0700, john larkin <jl@glen--canyon.com> >>wrote:
On Sun, 28 Sep 2025 22:50:51 +0100, Cursitor Doom <cd@notformail.com> >>>wrote:
On Sun, 28 Sep 2025 10:09:34 -0700, john larkin <jl@glen--canyon.com> >>>>wrote:
On Sun, 28 Sep 2025 17:38:40 +0100, Cursitor Doom <cd@notformail.com> >>>>>wrote:
On Sun, 28 Sep 2025 08:16:10 -0700, john larkin <jl@glen--canyon.com> >>>>>>wrote:
On Sun, 28 Sep 2025 09:04:52 +0100, Cursitor Doom <cd@notformail.com> >>>>>>>wrote:I've heard this term 'dive bar' before in popular songs. What exactly >>>>>>is that? I'm guessing some seedy joint where felonious types play >>>>>>pool?
On Sat, 27 Sep 2025 09:10:29 -0700, john larkin <jl@glen--canyon.com> >>>>>>>>wrote:
https://www.timeout.com/travel/coolest-neighbourhoods-in-the-world-2025
Two things I noticed is how many places have hideous overhead wires, >>>>>>>>>and how much signage is in English.
I lived in Berlin for some years in a delightful Kietz very similar to >>>>>>>>number 1 on this list: antiquarian booksellers on every street. Some >>>>>>>>really fascinating titles got published pre-1900; stuff that would >>>>>>>>never see the light of day now.
I modestly note that my little niche is #35 on the list. My little lab >>>>>>>is a two minute walk from GPS, which is an authentic old dive bar. >>>>>>
It's an old neighborhood bar that smells like an old neighborhood bar, >>>>>partonized by locals and worker-guys. It might have a pool table or a >>>>>fireplace. It has a few good but not fancy beers on tap.
The pizza place close by makes deliveries to your table at GPS. People >>>>>hate to let eating interfere with their drinking.
I asked the bar lady "Do you have any good rum, like Ron Zacapa?" and >>>>>>>she said "This ain't that kind of joint, honey."
Classic Americana. :-D
The Glen Park library is were they busted the Silk Road guy. A few >>>>>>>blocks away is (or emphatically was) the first dynamite factory in the >>>>>>>USA.
Oh dear! Go *bang* did it?
Yes. It lasted almost two years. They rebuilt it a couple miles to the >>>>>west, and that lasted two more.
https://www.dropbox.com/scl/fi/hi1j889kkn465fgpx5xgk/Glen_Canyon_Dynamite.jpg?rlkey=uq333s2okih26zgpicvcy7fb0&raw=1
Very quiet here today. Not even any of the regular trolls around.
Not much electronics here lately.
I need a small circuit to make +20 volts into -20 at maybe 400 mA. >>>>>There are lots of ways to do that.
I need to make 250VDC @ 150mA from 240VAC Gotta be low noise. Any >>>>suggestions?
There's not much in the way of commercial supplies in that range, and >>>nothing affordable.
I'd have thought *someone* must have such a supply, but as you say,
not much around.
A transformer+rectifier+filter should be OK.
What - you mean an isolation transformer or something with more
secodary turns?
Something like that.
What's the load going to be?
Plate voltages for 4x ECC83 toobs. They will run at above and below
250VDC, but it does change all sorts of parameters if they're tasked
to do that, so I'd prefer to stick to 250 for the sake of simplicity
and saves having to extrapolate from published data.
So you don't need regulation, and you can RC filter for the supply to
early single-ended stages.
Sounds like a classic toob amp. Do what they did.
On Wed, 01 Oct 2025 07:23:46 -0700, john larkin <jl@glen--canyon.com>
wrote:
On Wed, 01 Oct 2025 14:19:14 +0100, Cursitor Doom <cd@notformail.com> >>wrote:
On Mon, 29 Sep 2025 09:42:39 -0700, john larkin <jl@glen--canyon.com> >>>wrote:
On Sun, 28 Sep 2025 22:50:51 +0100, Cursitor Doom <cd@notformail.com> >>>>wrote:
On Sun, 28 Sep 2025 10:09:34 -0700, john larkin <jl@glen--canyon.com> >>>>>wrote:
On Sun, 28 Sep 2025 17:38:40 +0100, Cursitor Doom <cd@notformail.com> >>>>>>wrote:
On Sun, 28 Sep 2025 08:16:10 -0700, john larkin <jl@glen--canyon.com> >>>>>>>wrote:
On Sun, 28 Sep 2025 09:04:52 +0100, Cursitor Doom <cd@notformail.com> >>>>>>>>wrote:I've heard this term 'dive bar' before in popular songs. What exactly >>>>>>>is that? I'm guessing some seedy joint where felonious types play >>>>>>>pool?
On Sat, 27 Sep 2025 09:10:29 -0700, john larkin <jl@glen--canyon.com> >>>>>>>>>wrote:
https://www.timeout.com/travel/coolest-neighbourhoods-in-the-world-2025
Two things I noticed is how many places have hideous overhead wires, >>>>>>>>>>and how much signage is in English.
I lived in Berlin for some years in a delightful Kietz very similar to >>>>>>>>>number 1 on this list: antiquarian booksellers on every street. Some >>>>>>>>>really fascinating titles got published pre-1900; stuff that would >>>>>>>>>never see the light of day now.
I modestly note that my little niche is #35 on the list. My little lab >>>>>>>>is a two minute walk from GPS, which is an authentic old dive bar. >>>>>>>
It's an old neighborhood bar that smells like an old neighborhood bar, >>>>>>partonized by locals and worker-guys. It might have a pool table or a >>>>>>fireplace. It has a few good but not fancy beers on tap.
The pizza place close by makes deliveries to your table at GPS. People >>>>>>hate to let eating interfere with their drinking.
I asked the bar lady "Do you have any good rum, like Ron Zacapa?" and >>>>>>>>she said "This ain't that kind of joint, honey."
Classic Americana. :-D
The Glen Park library is were they busted the Silk Road guy. A few >>>>>>>>blocks away is (or emphatically was) the first dynamite factory in the >>>>>>>>USA.
Oh dear! Go *bang* did it?
Yes. It lasted almost two years. They rebuilt it a couple miles to the >>>>>>west, and that lasted two more.
https://www.dropbox.com/scl/fi/hi1j889kkn465fgpx5xgk/Glen_Canyon_Dynamite.jpg?rlkey=uq333s2okih26zgpicvcy7fb0&raw=1
Very quiet here today. Not even any of the regular trolls around.
Not much electronics here lately.
I need a small circuit to make +20 volts into -20 at maybe 400 mA. >>>>>>There are lots of ways to do that.
I need to make 250VDC @ 150mA from 240VAC Gotta be low noise. Any >>>>>suggestions?
There's not much in the way of commercial supplies in that range, and >>>>nothing affordable.
I'd have thought *someone* must have such a supply, but as you say,
not much around.
A transformer+rectifier+filter should be OK.
What - you mean an isolation transformer or something with more
secodary turns?
Something like that.
What's the load going to be?
Plate voltages for 4x ECC83 toobs. They will run at above and below >>>250VDC, but it does change all sorts of parameters if they're tasked
to do that, so I'd prefer to stick to 250 for the sake of simplicity
and saves having to extrapolate from published data.
So you don't need regulation, and you can RC filter for the supply to
early single-ended stages.
Sounds like a classic toob amp. Do what they did.
That is exactly what I'm not going to do, John. This may shock you,
but for the first time in 30 years on this group, I've decided to
actually *design* something!
There's a first time for everything, they
say, and God knows I've been told enough times over the years to go
design something for a change. Well that time has finally come. I've
been spending 99% of my time fixing up old vintage test equipment and
I fancy a change. And let's be honest: it's well overdue. Wish me
luck! :-)
On Wed, 01 Oct 2025 18:07:42 +0100, Cursitor Doom <cd@notformail.com>
wrote:
On Wed, 01 Oct 2025 07:23:46 -0700, john larkin <jl@glen--canyon.com> >>wrote:
On Wed, 01 Oct 2025 14:19:14 +0100, Cursitor Doom <cd@notformail.com> >>>wrote:
On Mon, 29 Sep 2025 09:42:39 -0700, john larkin <jl@glen--canyon.com> >>>>wrote:
On Sun, 28 Sep 2025 22:50:51 +0100, Cursitor Doom <cd@notformail.com> >>>>>wrote:
On Sun, 28 Sep 2025 10:09:34 -0700, john larkin <jl@glen--canyon.com> >>>>>>wrote:
On Sun, 28 Sep 2025 17:38:40 +0100, Cursitor Doom <cd@notformail.com> >>>>>>>wrote:
On Sun, 28 Sep 2025 08:16:10 -0700, john larkin <jl@glen--canyon.com> >>>>>>>>wrote:
On Sun, 28 Sep 2025 09:04:52 +0100, Cursitor Doom <cd@notformail.com> >>>>>>>>>wrote:I've heard this term 'dive bar' before in popular songs. What exactly >>>>>>>>is that? I'm guessing some seedy joint where felonious types play >>>>>>>>pool?
On Sat, 27 Sep 2025 09:10:29 -0700, john larkin <jl@glen--canyon.com> >>>>>>>>>>wrote:
https://www.timeout.com/travel/coolest-neighbourhoods-in-the-world-2025
Two things I noticed is how many places have hideous overhead wires, >>>>>>>>>>>and how much signage is in English.
I lived in Berlin for some years in a delightful Kietz very similar to
number 1 on this list: antiquarian booksellers on every street. Some >>>>>>>>>>really fascinating titles got published pre-1900; stuff that would >>>>>>>>>>never see the light of day now.
I modestly note that my little niche is #35 on the list. My little lab >>>>>>>>>is a two minute walk from GPS, which is an authentic old dive bar. >>>>>>>>
It's an old neighborhood bar that smells like an old neighborhood bar, >>>>>>>partonized by locals and worker-guys. It might have a pool table or a >>>>>>>fireplace. It has a few good but not fancy beers on tap.
The pizza place close by makes deliveries to your table at GPS. People >>>>>>>hate to let eating interfere with their drinking.
I asked the bar lady "Do you have any good rum, like Ron Zacapa?" and >>>>>>>>>she said "This ain't that kind of joint, honey."
Classic Americana. :-D
The Glen Park library is were they busted the Silk Road guy. A few >>>>>>>>>blocks away is (or emphatically was) the first dynamite factory in the >>>>>>>>>USA.
Oh dear! Go *bang* did it?
Yes. It lasted almost two years. They rebuilt it a couple miles to the >>>>>>>west, and that lasted two more.
https://www.dropbox.com/scl/fi/hi1j889kkn465fgpx5xgk/Glen_Canyon_Dynamite.jpg?rlkey=uq333s2okih26zgpicvcy7fb0&raw=1
Very quiet here today. Not even any of the regular trolls around. >>>>>>>
Not much electronics here lately.
I need a small circuit to make +20 volts into -20 at maybe 400 mA. >>>>>>>There are lots of ways to do that.
I need to make 250VDC @ 150mA from 240VAC Gotta be low noise. Any >>>>>>suggestions?
There's not much in the way of commercial supplies in that range, and >>>>>nothing affordable.
I'd have thought *someone* must have such a supply, but as you say,
not much around.
A transformer+rectifier+filter should be OK.
What - you mean an isolation transformer or something with more >>>>secodary turns?
Something like that.
What's the load going to be?
Plate voltages for 4x ECC83 toobs. They will run at above and below >>>>250VDC, but it does change all sorts of parameters if they're tasked
to do that, so I'd prefer to stick to 250 for the sake of simplicity >>>>and saves having to extrapolate from published data.
Tubes are wildly variant. The data sheets are just sorta
approximations, so I wouldn't sweat a few volts.
Tubes vary so much that people used to sell matched pairs. That was
before negative feedback was invented.
So you don't need regulation, and you can RC filter for the supply to >>>early single-ended stages.
Sounds like a classic toob amp. Do what they did.
That is exactly what I'm not going to do, John. This may shock you,
but for the first time in 30 years on this group, I've decided to
actually *design* something!
Ack! That's unprecidented here.
There's a first time for everything, they
say, and God knows I've been told enough times over the years to go
design something for a change. Well that time has finally come. I've
been spending 99% of my time fixing up old vintage test equipment and
I fancy a change. And let's be honest: it's well overdue. Wish me
luck! :-)
Yes. Let me know if I can help. We have a lot of parts in stock, but
no tubes or octal sockets or cloth-covered wire or like that.
I started designing with tubes when I was a kid. They were free and a
CK722 germanium transistor cost $7.
On Wed, 01 Oct 2025 10:39:09 -0700, john larkin <jl@glen--canyon.com>
wrote:
On Wed, 01 Oct 2025 18:07:42 +0100, Cursitor Doom <cd@notformail.com> >>wrote:
On Wed, 01 Oct 2025 07:23:46 -0700, john larkin <jl@glen--canyon.com> >>>wrote:
On Wed, 01 Oct 2025 14:19:14 +0100, Cursitor Doom <cd@notformail.com> >>>>wrote:
On Mon, 29 Sep 2025 09:42:39 -0700, john larkin <jl@glen--canyon.com> >>>>>wrote:
On Sun, 28 Sep 2025 22:50:51 +0100, Cursitor Doom <cd@notformail.com> >>>>>>wrote:
On Sun, 28 Sep 2025 10:09:34 -0700, john larkin <jl@glen--canyon.com> >>>>>>>wrote:
On Sun, 28 Sep 2025 17:38:40 +0100, Cursitor Doom <cd@notformail.com> >>>>>>>>wrote:
On Sun, 28 Sep 2025 08:16:10 -0700, john larkin <jl@glen--canyon.com> >>>>>>>>>wrote:
On Sun, 28 Sep 2025 09:04:52 +0100, Cursitor Doom <cd@notformail.com> >>>>>>>>>>wrote:I've heard this term 'dive bar' before in popular songs. What exactly >>>>>>>>>is that? I'm guessing some seedy joint where felonious types play >>>>>>>>>pool?
On Sat, 27 Sep 2025 09:10:29 -0700, john larkin <jl@glen--canyon.com>
wrote:
https://www.timeout.com/travel/coolest-neighbourhoods-in-the-world-2025
Two things I noticed is how many places have hideous overhead wires,
and how much signage is in English.
I lived in Berlin for some years in a delightful Kietz very similar to
number 1 on this list: antiquarian booksellers on every street. Some >>>>>>>>>>>really fascinating titles got published pre-1900; stuff that would >>>>>>>>>>>never see the light of day now.
I modestly note that my little niche is #35 on the list. My little lab
is a two minute walk from GPS, which is an authentic old dive bar. >>>>>>>>>
It's an old neighborhood bar that smells like an old neighborhood bar, >>>>>>>>partonized by locals and worker-guys. It might have a pool table or a >>>>>>>>fireplace. It has a few good but not fancy beers on tap.
The pizza place close by makes deliveries to your table at GPS. People >>>>>>>>hate to let eating interfere with their drinking.
I asked the bar lady "Do you have any good rum, like Ron Zacapa?" and >>>>>>>>>>she said "This ain't that kind of joint, honey."
Classic Americana. :-D
The Glen Park library is were they busted the Silk Road guy. A few >>>>>>>>>>blocks away is (or emphatically was) the first dynamite factory in the
USA.
Oh dear! Go *bang* did it?
Yes. It lasted almost two years. They rebuilt it a couple miles to the >>>>>>>>west, and that lasted two more.
https://www.dropbox.com/scl/fi/hi1j889kkn465fgpx5xgk/Glen_Canyon_Dynamite.jpg?rlkey=uq333s2okih26zgpicvcy7fb0&raw=1
Very quiet here today. Not even any of the regular trolls around. >>>>>>>>
Not much electronics here lately.
I need a small circuit to make +20 volts into -20 at maybe 400 mA. >>>>>>>>There are lots of ways to do that.
I need to make 250VDC @ 150mA from 240VAC Gotta be low noise. Any >>>>>>>suggestions?
There's not much in the way of commercial supplies in that range, and >>>>>>nothing affordable.
I'd have thought *someone* must have such a supply, but as you say, >>>>>not much around.
A transformer+rectifier+filter should be OK.
What - you mean an isolation transformer or something with more >>>>>secodary turns?
Something like that.
What's the load going to be?
Plate voltages for 4x ECC83 toobs. They will run at above and below >>>>>250VDC, but it does change all sorts of parameters if they're tasked >>>>>to do that, so I'd prefer to stick to 250 for the sake of simplicity >>>>>and saves having to extrapolate from published data.
Tubes are wildly variant. The data sheets are just sorta
approximations, so I wouldn't sweat a few volts.
Tubes vary so much that people used to sell matched pairs. That was
before negative feedback was invented.
BJTs are notorious for that, too. And people also selected matched
pairs of those for the same reason.
So you don't need regulation, and you can RC filter for the supply to >>>>early single-ended stages.
Sounds like a classic toob amp. Do what they did.
That is exactly what I'm not going to do, John. This may shock you,
but for the first time in 30 years on this group, I've decided to >>>actually *design* something!
Ack! That's unprecidented here.
Certainly is in my case! :-)
There's a first time for everything, they
say, and God knows I've been told enough times over the years to go >>>design something for a change. Well that time has finally come. I've
been spending 99% of my time fixing up old vintage test equipment and
I fancy a change. And let's be honest: it's well overdue. Wish me
luck! :-)
Yes. Let me know if I can help. We have a lot of parts in stock, but
no tubes or octal sockets or cloth-covered wire or like that.
I have the tubes. The sockets: some I have, some I'll need to order. I
was planning to make it all-tube, but difficulty in finding decent
quality output transformers of the right spec put paid to that. So now
it's to be a hybrid: tube front end going into BJTs for the current >amplification side of things.
I started designing with tubes when I was a kid. They were free and a
CK722 germanium transistor cost $7.
Same here. But over the decades I'd forgotten much about them. I
couldn't even recall whether grids had to be above or below cathode >potential! I just want to do something a bit different. Been messing
around with semis for far too long; time to get back to my roots.
over the decades I'd forgotten much about them. I
couldn't even recall whether grids had to be above or below cathode potential!
On Thu, 02 Oct 2025 00:05:19 +0100, Cursitor Doom <cd@notformail.com>
wrote:
On Wed, 01 Oct 2025 10:39:09 -0700, john larkin <jl@glen--canyon.com> >>wrote:
On Wed, 01 Oct 2025 18:07:42 +0100, Cursitor Doom <cd@notformail.com> >>>wrote:
On Wed, 01 Oct 2025 07:23:46 -0700, john larkin <jl@glen--canyon.com> >>>>wrote:
On Wed, 01 Oct 2025 14:19:14 +0100, Cursitor Doom <cd@notformail.com> >>>>>wrote:
On Mon, 29 Sep 2025 09:42:39 -0700, john larkin <jl@glen--canyon.com> >>>>>>wrote:
On Sun, 28 Sep 2025 22:50:51 +0100, Cursitor Doom <cd@notformail.com> >>>>>>>wrote:
On Sun, 28 Sep 2025 10:09:34 -0700, john larkin <jl@glen--canyon.com> >>>>>>>>wrote:
On Sun, 28 Sep 2025 17:38:40 +0100, Cursitor Doom <cd@notformail.com> >>>>>>>>>wrote:
On Sun, 28 Sep 2025 08:16:10 -0700, john larkin <jl@glen--canyon.com> >>>>>>>>>>wrote:
On Sun, 28 Sep 2025 09:04:52 +0100, Cursitor Doom <cd@notformail.com>I've heard this term 'dive bar' before in popular songs. What exactly >>>>>>>>>>is that? I'm guessing some seedy joint where felonious types play >>>>>>>>>>pool?
wrote:
On Sat, 27 Sep 2025 09:10:29 -0700, john larkin <jl@glen--canyon.com>
wrote:
https://www.timeout.com/travel/coolest-neighbourhoods-in-the-world-2025
Two things I noticed is how many places have hideous overhead wires,
and how much signage is in English.
I lived in Berlin for some years in a delightful Kietz very similar to
number 1 on this list: antiquarian booksellers on every street. Some
really fascinating titles got published pre-1900; stuff that would >>>>>>>>>>>>never see the light of day now.
I modestly note that my little niche is #35 on the list. My little lab
is a two minute walk from GPS, which is an authentic old dive bar. >>>>>>>>>>
It's an old neighborhood bar that smells like an old neighborhood bar, >>>>>>>>>partonized by locals and worker-guys. It might have a pool table or a >>>>>>>>>fireplace. It has a few good but not fancy beers on tap.
The pizza place close by makes deliveries to your table at GPS. People >>>>>>>>>hate to let eating interfere with their drinking.
I asked the bar lady "Do you have any good rum, like Ron Zacapa?" and
she said "This ain't that kind of joint, honey."
Classic Americana. :-D
The Glen Park library is were they busted the Silk Road guy. A few >>>>>>>>>>>blocks away is (or emphatically was) the first dynamite factory in the
USA.
Oh dear! Go *bang* did it?
Yes. It lasted almost two years. They rebuilt it a couple miles to the >>>>>>>>>west, and that lasted two more.
https://www.dropbox.com/scl/fi/hi1j889kkn465fgpx5xgk/Glen_Canyon_Dynamite.jpg?rlkey=uq333s2okih26zgpicvcy7fb0&raw=1
Very quiet here today. Not even any of the regular trolls around. >>>>>>>>>
Not much electronics here lately.
I need a small circuit to make +20 volts into -20 at maybe 400 mA. >>>>>>>>>There are lots of ways to do that.
I need to make 250VDC @ 150mA from 240VAC Gotta be low noise. Any >>>>>>>>suggestions?
There's not much in the way of commercial supplies in that range, and >>>>>>>nothing affordable.
I'd have thought *someone* must have such a supply, but as you say, >>>>>>not much around.
A transformer+rectifier+filter should be OK.
What - you mean an isolation transformer or something with more >>>>>>secodary turns?
Something like that.
What's the load going to be?
Plate voltages for 4x ECC83 toobs. They will run at above and below >>>>>>250VDC, but it does change all sorts of parameters if they're tasked >>>>>>to do that, so I'd prefer to stick to 250 for the sake of simplicity >>>>>>and saves having to extrapolate from published data.
Tubes are wildly variant. The data sheets are just sorta
approximations, so I wouldn't sweat a few volts.
Tubes vary so much that people used to sell matched pairs. That was >>>before negative feedback was invented.
BJTs are notorious for that, too. And people also selected matched
pairs of those for the same reason.
So you don't need regulation, and you can RC filter for the supply to >>>>>early single-ended stages.
Sounds like a classic toob amp. Do what they did.
That is exactly what I'm not going to do, John. This may shock you,
but for the first time in 30 years on this group, I've decided to >>>>actually *design* something!
Ack! That's unprecidented here.
Certainly is in my case! :-)
There's a first time for everything, they
say, and God knows I've been told enough times over the years to go >>>>design something for a change. Well that time has finally come. I've >>>>been spending 99% of my time fixing up old vintage test equipment and >>>>I fancy a change. And let's be honest: it's well overdue. Wish me
luck! :-)
Yes. Let me know if I can help. We have a lot of parts in stock, but
no tubes or octal sockets or cloth-covered wire or like that.
I have the tubes. The sockets: some I have, some I'll need to order. I
was planning to make it all-tube, but difficulty in finding decent
quality output transformers of the right spec put paid to that. So now
it's to be a hybrid: tube front end going into BJTs for the current >>amplification side of things.
Or mosfets.
I started designing with tubes when I was a kid. They were free and a >>>CK722 germanium transistor cost $7.
Same here. But over the decades I'd forgotten much about them. I
couldn't even recall whether grids had to be above or below cathode >>potential! I just want to do something a bit different. Been messing
around with semis for far too long; time to get back to my roots.
Tubes are usually run in depletion mode, but nasty class-C RF ones are >sometimes run with serious positive grid swing. You can see the grids >glowing.
Tubes are awful.
John Larkin--- Synchronet 3.21a-Linux NewsLink 1.2
Highland Tech Glen Canyon Design Center
Lunatic Fringe Electronics
Cursitor Doom <cd@notformail.com> wrote:
[...]
over the decades I'd forgotten much about them. I
couldn't even recall whether grids had to be above or below cathode
potential!
If the cathode glows but the grid doesn't, you have got it the right way >around.
On Thu, 2 Oct 2025 10:30:21 +0100, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:
Cursitor Doom <cd@notformail.com> wrote:
[...]
over the decades I'd forgotten much about them. I
couldn't even recall whether grids had to be above or below cathode
potential!
If the cathode glows but the grid doesn't, you have got it the right way >around.
If the cathodes are glowing I'd have done something wrong!
Cursitor Doom <cd@notformail.com> wrote:
On Thu, 2 Oct 2025 10:30:21 +0100, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:
Cursitor Doom <cd@notformail.com> wrote:
[...]
over the decades I'd forgotten much about them. I
couldn't even recall whether grids had to be above or below cathode
potential!
If the cathode glows but the grid doesn't, you have got it the right way
around.
If the cathodes are glowing I'd have done something wrong!
If they aren't, you've forgotten to switch it on.
On Wed, 01 Oct 2025 18:07:42 +0100, Cursitor Doom <cd@notformail.com>....
wrote:
On Wed, 01 Oct 2025 07:23:46 -0700, john larkin <jl@glen--canyon.com> >>wrote:
On Wed, 01 Oct 2025 14:19:14 +0100, Cursitor Doom <cd@notformail.com> >>>wrote:
On Mon, 29 Sep 2025 09:42:39 -0700, john larkin <jl@glen--canyon.com> >>>>wrote:
On Sun, 28 Sep 2025 22:50:51 +0100, Cursitor Doom <cd@notformail.com> >>>>>wrote:
On Sun, 28 Sep 2025 10:09:34 -0700, john larkin <jl@glen--canyon.com> >>>>>>wrote:
On Sun, 28 Sep 2025 17:38:40 +0100, Cursitor Doom <cd@notformail.com> >>>>>>>wrote:
On Sun, 28 Sep 2025 08:16:10 -0700, john larkin <jl@glen--canyon.com> >>>>>>>>wrote:
On Sun, 28 Sep 2025 09:04:52 +0100, Cursitor Doom <cd@notformail.com> >>>>>>>>>wrote:I've heard this term 'dive bar' before in popular songs. What exactly >>>>>>>>is that? I'm guessing some seedy joint where felonious types play >>>>>>>>pool?
On Sat, 27 Sep 2025 09:10:29 -0700, john larkin <jl@glen--canyon.com> >>>>>>>>>>wrote:
https://www.timeout.com/travel/coolest-neighbourhoods-in-the-world-2025
Two things I noticed is how many places have hideous overhead wires, >>>>>>>>>>>and how much signage is in English.
I lived in Berlin for some years in a delightful Kietz very similar to
number 1 on this list: antiquarian booksellers on every street. Some >>>>>>>>>>really fascinating titles got published pre-1900; stuff that would >>>>>>>>>>never see the light of day now.
I modestly note that my little niche is #35 on the list. My little lab >>>>>>>>>is a two minute walk from GPS, which is an authentic old dive bar. >>>>>>>>
Sounds like a classic toob amp. Do what they did.
That is exactly what I'm not going to do, John. This may shock you,
but for the first time in 30 years on this group, I've decided to
actually *design* something!
Ack! That's unprecidented here.
There's a first time for everything, they
say, and God knows I've been told enough times over the years to go
design something for a change. Well that time has finally come. I've
been spending 99% of my time fixing up old vintage test equipment and
I fancy a change. And let's be honest: it's well overdue. Wish me
luck! :-)
Yes. Let me know if I can help. We have a lot of parts in stock, but
no tubes or octal sockets or cloth-covered wire or like that.
I started designing with tubes when I was a kid. They were free and a
CK722 germanium transistor cost $7.
John Larkin
Highland Tech Glen Canyon Design Center
Lunatic Fringe Electronics
On Wed, 01 Oct 2025 16:49:21 -0700, john larkin <jl@glen--canyon.com>
wrote:
On Thu, 02 Oct 2025 00:05:19 +0100, Cursitor Doom <cd@notformail.com> >>wrote:
On Wed, 01 Oct 2025 10:39:09 -0700, john larkin <jl@glen--canyon.com> >>>wrote:
On Wed, 01 Oct 2025 18:07:42 +0100, Cursitor Doom <cd@notformail.com> >>>>wrote:
On Wed, 01 Oct 2025 07:23:46 -0700, john larkin <jl@glen--canyon.com> >>>>>wrote:
On Wed, 01 Oct 2025 14:19:14 +0100, Cursitor Doom <cd@notformail.com> >>>>>>wrote:
On Mon, 29 Sep 2025 09:42:39 -0700, john larkin <jl@glen--canyon.com> >>>>>>>wrote:
On Sun, 28 Sep 2025 22:50:51 +0100, Cursitor Doom <cd@notformail.com> >>>>>>>>wrote:
On Sun, 28 Sep 2025 10:09:34 -0700, john larkin <jl@glen--canyon.com> >>>>>>>>>wrote:
On Sun, 28 Sep 2025 17:38:40 +0100, Cursitor Doom <cd@notformail.com> >>>>>>>>>>wrote:
On Sun, 28 Sep 2025 08:16:10 -0700, john larkin <jl@glen--canyon.com>
wrote:
On Sun, 28 Sep 2025 09:04:52 +0100, Cursitor Doom <cd@notformail.com>I've heard this term 'dive bar' before in popular songs. What exactly
wrote:
On Sat, 27 Sep 2025 09:10:29 -0700, john larkin <jl@glen--canyon.com>
wrote:
https://www.timeout.com/travel/coolest-neighbourhoods-in-the-world-2025
Two things I noticed is how many places have hideous overhead wires,
and how much signage is in English.
I lived in Berlin for some years in a delightful Kietz very similar to
number 1 on this list: antiquarian booksellers on every street. Some
really fascinating titles got published pre-1900; stuff that would >>>>>>>>>>>>>never see the light of day now.
I modestly note that my little niche is #35 on the list. My little lab
is a two minute walk from GPS, which is an authentic old dive bar. >>>>>>>>>>>
is that? I'm guessing some seedy joint where felonious types play >>>>>>>>>>>pool?
It's an old neighborhood bar that smells like an old neighborhood bar,
partonized by locals and worker-guys. It might have a pool table or a
fireplace. It has a few good but not fancy beers on tap.
The pizza place close by makes deliveries to your table at GPS. People
hate to let eating interfere with their drinking.
I asked the bar lady "Do you have any good rum, like Ron Zacapa?" and
she said "This ain't that kind of joint, honey."
Classic Americana. :-D
The Glen Park library is were they busted the Silk Road guy. A few >>>>>>>>>>>>blocks away is (or emphatically was) the first dynamite factory in the
USA.
Oh dear! Go *bang* did it?
Yes. It lasted almost two years. They rebuilt it a couple miles to the
west, and that lasted two more.
https://www.dropbox.com/scl/fi/hi1j889kkn465fgpx5xgk/Glen_Canyon_Dynamite.jpg?rlkey=uq333s2okih26zgpicvcy7fb0&raw=1
Very quiet here today. Not even any of the regular trolls around. >>>>>>>>>>
Not much electronics here lately.
I need a small circuit to make +20 volts into -20 at maybe 400 mA. >>>>>>>>>>There are lots of ways to do that.
I need to make 250VDC @ 150mA from 240VAC Gotta be low noise. Any >>>>>>>>>suggestions?
There's not much in the way of commercial supplies in that range, and >>>>>>>>nothing affordable.
I'd have thought *someone* must have such a supply, but as you say, >>>>>>>not much around.
A transformer+rectifier+filter should be OK.
What - you mean an isolation transformer or something with more >>>>>>>secodary turns?
Something like that.
What's the load going to be?
Plate voltages for 4x ECC83 toobs. They will run at above and below >>>>>>>250VDC, but it does change all sorts of parameters if they're tasked >>>>>>>to do that, so I'd prefer to stick to 250 for the sake of simplicity >>>>>>>and saves having to extrapolate from published data.
Tubes are wildly variant. The data sheets are just sorta >>>>approximations, so I wouldn't sweat a few volts.
Tubes vary so much that people used to sell matched pairs. That was >>>>before negative feedback was invented.
BJTs are notorious for that, too. And people also selected matched
pairs of those for the same reason.
So you don't need regulation, and you can RC filter for the supply to >>>>>>early single-ended stages.
Sounds like a classic toob amp. Do what they did.
That is exactly what I'm not going to do, John. This may shock you, >>>>>but for the first time in 30 years on this group, I've decided to >>>>>actually *design* something!
Ack! That's unprecidented here.
Certainly is in my case! :-)
There's a first time for everything, they
say, and God knows I've been told enough times over the years to go >>>>>design something for a change. Well that time has finally come. I've >>>>>been spending 99% of my time fixing up old vintage test equipment and >>>>>I fancy a change. And let's be honest: it's well overdue. Wish me >>>>>luck! :-)
Yes. Let me know if I can help. We have a lot of parts in stock, but
no tubes or octal sockets or cloth-covered wire or like that.
I have the tubes. The sockets: some I have, some I'll need to order. I >>>was planning to make it all-tube, but difficulty in finding decent >>>quality output transformers of the right spec put paid to that. So now >>>it's to be a hybrid: tube front end going into BJTs for the current >>>amplification side of things.
Or mosfets.
Well, I'm aware Mosfets are used for certain exotic amplifier modes
(can't recall exactly which but might be class D or G or something)
but I'm going full traditional here with class A or AB perhaps. And
you can't use Mosfets for that AFAICS. But sure, if you're going to
chop up the signal and mess around with it, Mosfets are ideal.
I started designing with tubes when I was a kid. They were free and a >>>>CK722 germanium transistor cost $7.
Same here. But over the decades I'd forgotten much about them. I
couldn't even recall whether grids had to be above or below cathode >>>potential! I just want to do something a bit different. Been messing >>>around with semis for far too long; time to get back to my roots.
Tubes are usually run in depletion mode, but nasty class-C RF ones are >>sometimes run with serious positive grid swing. You can see the grids >>glowing.
Tubes are awful.
Bit of a sweeping generalization there, John!
Cursitor Doom <cd@notformail.com> wrote:
[...]
over the decades I'd forgotten much about them. I
couldn't even recall whether grids had to be above or below cathode
potential!
If the cathode glows but the grid doesn't, you have got it the right way >around.
On Thu, 02 Oct 2025 12:59:25 +0100, Cursitor Doom <cd@notformail.com>
wrote:
On Wed, 01 Oct 2025 16:49:21 -0700, john larkin <jl@glen--canyon.com> >>wrote:
On Thu, 02 Oct 2025 00:05:19 +0100, Cursitor Doom <cd@notformail.com> >>>wrote:
On Wed, 01 Oct 2025 10:39:09 -0700, john larkin <jl@glen--canyon.com> >>>>wrote:
On Wed, 01 Oct 2025 18:07:42 +0100, Cursitor Doom <cd@notformail.com> >>>>>wrote:
On Wed, 01 Oct 2025 07:23:46 -0700, john larkin <jl@glen--canyon.com> >>>>>>wrote:
On Wed, 01 Oct 2025 14:19:14 +0100, Cursitor Doom <cd@notformail.com> >>>>>>>wrote:
On Mon, 29 Sep 2025 09:42:39 -0700, john larkin <jl@glen--canyon.com> >>>>>>>>wrote:
On Sun, 28 Sep 2025 22:50:51 +0100, Cursitor Doom <cd@notformail.com> >>>>>>>>>wrote:
On Sun, 28 Sep 2025 10:09:34 -0700, john larkin <jl@glen--canyon.com> >>>>>>>>>>wrote:
On Sun, 28 Sep 2025 17:38:40 +0100, Cursitor Doom <cd@notformail.com>
wrote:
On Sun, 28 Sep 2025 08:16:10 -0700, john larkin <jl@glen--canyon.com>
wrote:
On Sun, 28 Sep 2025 09:04:52 +0100, Cursitor Doom <cd@notformail.com>I've heard this term 'dive bar' before in popular songs. What exactly
wrote:
On Sat, 27 Sep 2025 09:10:29 -0700, john larkin <jl@glen--canyon.com>
wrote:
https://www.timeout.com/travel/coolest-neighbourhoods-in-the-world-2025
Two things I noticed is how many places have hideous overhead wires,
and how much signage is in English.
I lived in Berlin for some years in a delightful Kietz very similar to
number 1 on this list: antiquarian booksellers on every street. Some
really fascinating titles got published pre-1900; stuff that would
never see the light of day now.
I modestly note that my little niche is #35 on the list. My little lab
is a two minute walk from GPS, which is an authentic old dive bar. >>>>>>>>>>>>
is that? I'm guessing some seedy joint where felonious types play >>>>>>>>>>>>pool?
It's an old neighborhood bar that smells like an old neighborhood bar,
partonized by locals and worker-guys. It might have a pool table or a
fireplace. It has a few good but not fancy beers on tap.
The pizza place close by makes deliveries to your table at GPS. People
hate to let eating interfere with their drinking.
I asked the bar lady "Do you have any good rum, like Ron Zacapa?" and
she said "This ain't that kind of joint, honey."
Classic Americana. :-D
The Glen Park library is were they busted the Silk Road guy. A few >>>>>>>>>>>>>blocks away is (or emphatically was) the first dynamite factory in the
USA.
Oh dear! Go *bang* did it?
Yes. It lasted almost two years. They rebuilt it a couple miles to the
west, and that lasted two more.
https://www.dropbox.com/scl/fi/hi1j889kkn465fgpx5xgk/Glen_Canyon_Dynamite.jpg?rlkey=uq333s2okih26zgpicvcy7fb0&raw=1
Very quiet here today. Not even any of the regular trolls around. >>>>>>>>>>>
Not much electronics here lately.
I need a small circuit to make +20 volts into -20 at maybe 400 mA. >>>>>>>>>>>There are lots of ways to do that.
I need to make 250VDC @ 150mA from 240VAC Gotta be low noise. Any >>>>>>>>>>suggestions?
There's not much in the way of commercial supplies in that range, and >>>>>>>>>nothing affordable.
I'd have thought *someone* must have such a supply, but as you say, >>>>>>>>not much around.
A transformer+rectifier+filter should be OK.
What - you mean an isolation transformer or something with more >>>>>>>>secodary turns?
Something like that.
What's the load going to be?
Plate voltages for 4x ECC83 toobs. They will run at above and below >>>>>>>>250VDC, but it does change all sorts of parameters if they're tasked >>>>>>>>to do that, so I'd prefer to stick to 250 for the sake of simplicity >>>>>>>>and saves having to extrapolate from published data.
Tubes are wildly variant. The data sheets are just sorta >>>>>approximations, so I wouldn't sweat a few volts.
Tubes vary so much that people used to sell matched pairs. That was >>>>>before negative feedback was invented.
BJTs are notorious for that, too. And people also selected matched >>>>pairs of those for the same reason.
So you don't need regulation, and you can RC filter for the supply to >>>>>>>early single-ended stages.
Sounds like a classic toob amp. Do what they did.
That is exactly what I'm not going to do, John. This may shock you, >>>>>>but for the first time in 30 years on this group, I've decided to >>>>>>actually *design* something!
Ack! That's unprecidented here.
Certainly is in my case! :-)
There's a first time for everything, they
say, and God knows I've been told enough times over the years to go >>>>>>design something for a change. Well that time has finally come. I've >>>>>>been spending 99% of my time fixing up old vintage test equipment and >>>>>>I fancy a change. And let's be honest: it's well overdue. Wish me >>>>>>luck! :-)
Yes. Let me know if I can help. We have a lot of parts in stock, but >>>>>no tubes or octal sockets or cloth-covered wire or like that.
I have the tubes. The sockets: some I have, some I'll need to order. I >>>>was planning to make it all-tube, but difficulty in finding decent >>>>quality output transformers of the right spec put paid to that. So now >>>>it's to be a hybrid: tube front end going into BJTs for the current >>>>amplification side of things.
Or mosfets.
Well, I'm aware Mosfets are used for certain exotic amplifier modes
(can't recall exactly which but might be class D or G or something)
but I'm going full traditional here with class A or AB perhaps. And
you can't use Mosfets for that AFAICS. But sure, if you're going to
chop up the signal and mess around with it, Mosfets are ideal.
Mosfets can work fine in linear amps, but you've got to be careful
about their safe operating area. A lot of fets are optimized for fast >switching. We test them to be safe.
https://www.dropbox.com/scl/fi/oq1bgzkpsdcsmrg63w1r9/ExFets.jpg?rlkey=jcscvg5vt1qebgyxb0gt5575q&dl=0
We use one mosfet that's rated for 1000 amps and 1000 watts.
If you hang an opamp on a mosfet, it becomes ultra-linear.
--- Synchronet 3.21a-Linux NewsLink 1.2
I started designing with tubes when I was a kid. They were free and a >>>>>CK722 germanium transistor cost $7.
Same here. But over the decades I'd forgotten much about them. I >>>>couldn't even recall whether grids had to be above or below cathode >>>>potential! I just want to do something a bit different. Been messing >>>>around with semis for far too long; time to get back to my roots.
Tubes are usually run in depletion mode, but nasty class-C RF ones are >>>sometimes run with serious positive grid swing. You can see the grids >>>glowing.
Tubes are awful.
Bit of a sweeping generalization there, John!
It's true! They are expensive, unreliable, big, and fragile.
Some exotica, magnetrons and TWTs and krytrons and some imaging
things, still make sense.
John Larkin
Highland Tech Glen Canyon Design Center
Lunatic Fringe Electronics
On Thu, 2 Oct 2025 10:30:21 +0100, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:
Cursitor Doom <cd@notformail.com> wrote:
[...]
over the decades I'd forgotten much about them. I
couldn't even recall whether grids had to be above or below cathode
potential!
If the cathode glows but the grid doesn't, you have got it the right way >>around.
In a serious class C RF power amp, with amps of grid current,
everything glows.
I think few radio or TV stations still use tubes.--- Synchronet 3.21a-Linux NewsLink 1.2
John Larkin
Highland Tech Glen Canyon Design Center
Lunatic Fringe Electronics
On Wed, 01 Oct 2025 10:39:09 -0700, john larkin <jl@glen--canyon.com>
wrote:
On Wed, 01 Oct 2025 18:07:42 +0100, Cursitor Doom <cd@notformail.com>
wrote:
On Wed, 01 Oct 2025 07:23:46 -0700, john larkin <jl@glen--canyon.com>
wrote:
On Wed, 01 Oct 2025 14:19:14 +0100, Cursitor Doom <cd@notformail.com>
wrote:
On Mon, 29 Sep 2025 09:42:39 -0700, john larkin <jl@glen--canyon.com> >>>>> wrote:
On Sun, 28 Sep 2025 22:50:51 +0100, Cursitor Doom <cd@notformail.com> >>>>>> wrote:
On Sun, 28 Sep 2025 10:09:34 -0700, john larkin <jl@glen--canyon.com> >>>>>>> wrote:
On Sun, 28 Sep 2025 17:38:40 +0100, Cursitor Doom <cd@notformail.com> >>>>>>>> wrote:
On Sun, 28 Sep 2025 08:16:10 -0700, john larkin <jl@glen--canyon.com> >>>>>>>>> wrote:
On Sun, 28 Sep 2025 09:04:52 +0100, Cursitor Doom <cd@notformail.com>I've heard this term 'dive bar' before in popular songs. What exactly >>>>>>>>> is that? I'm guessing some seedy joint where felonious types play >>>>>>>>> pool?
wrote:
On Sat, 27 Sep 2025 09:10:29 -0700, john larkin <jl@glen--canyon.com>
wrote:
https://www.timeout.com/travel/coolest-neighbourhoods-in-the-world-2025
Two things I noticed is how many places have hideous overhead wires,
and how much signage is in English.
I lived in Berlin for some years in a delightful Kietz very similar to
number 1 on this list: antiquarian booksellers on every street. Some
really fascinating titles got published pre-1900; stuff that would >>>>>>>>>>> never see the light of day now.
I modestly note that my little niche is #35 on the list. My little lab
is a two minute walk from GPS, which is an authentic old dive bar. >>>>>>>>>
It's an old neighborhood bar that smells like an old neighborhood bar, >>>>>>>> partonized by locals and worker-guys. It might have a pool table or a >>>>>>>> fireplace. It has a few good but not fancy beers on tap.
The pizza place close by makes deliveries to your table at GPS. People >>>>>>>> hate to let eating interfere with their drinking.
I asked the bar lady "Do you have any good rum, like Ron Zacapa?" and
she said "This ain't that kind of joint, honey."
Classic Americana. :-D
The Glen Park library is were they busted the Silk Road guy. A few >>>>>>>>>> blocks away is (or emphatically was) the first dynamite factory in the
USA.
Oh dear! Go *bang* did it?
Yes. It lasted almost two years. They rebuilt it a couple miles to the >>>>>>>> west, and that lasted two more.
https://www.dropbox.com/scl/fi/hi1j889kkn465fgpx5xgk/Glen_Canyon_Dynamite.jpg?rlkey=uq333s2okih26zgpicvcy7fb0&raw=1
Very quiet here today. Not even any of the regular trolls around. >>>>>>>>
Not much electronics here lately.
I need a small circuit to make +20 volts into -20 at maybe 400 mA. >>>>>>>> There are lots of ways to do that.
I need to make 250VDC @ 150mA from 240VAC Gotta be low noise. Any >>>>>>> suggestions?
There's not much in the way of commercial supplies in that range, and >>>>>> nothing affordable.
I'd have thought *someone* must have such a supply, but as you say,
not much around.
A transformer+rectifier+filter should be OK.
What - you mean an isolation transformer or something with more
secodary turns?
Something like that.
What's the load going to be?
Plate voltages for 4x ECC83 toobs. They will run at above and below
250VDC, but it does change all sorts of parameters if they're tasked >>>>> to do that, so I'd prefer to stick to 250 for the sake of simplicity >>>>> and saves having to extrapolate from published data.
Tubes are wildly variant. The data sheets are just sorta
approximations, so I wouldn't sweat a few volts.
Tubes vary so much that people used to sell matched pairs. That was
before negative feedback was invented.
BJTs are notorious for that, too. And people also selected matched
pairs of those for the same reason.
So you don't need regulation, and you can RC filter for the supply to
early single-ended stages.
Sounds like a classic toob amp. Do what they did.
That is exactly what I'm not going to do, John. This may shock you,
but for the first time in 30 years on this group, I've decided to
actually *design* something!
Ack! That's unprecidented here.
Certainly is in my case! :-)
There's a first time for everything, they
say, and God knows I've been told enough times over the years to go
design something for a change. Well that time has finally come. I've
been spending 99% of my time fixing up old vintage test equipment and
I fancy a change. And let's be honest: it's well overdue. Wish me
luck! :-)
Yes. Let me know if I can help. We have a lot of parts in stock, but
no tubes or octal sockets or cloth-covered wire or like that.
I have the tubes. The sockets: some I have, some I'll need to order. I
was planning to make it all-tube, but difficulty in finding decent
quality output transformers of the right spec put paid to that. So now
it's to be a hybrid: tube front end going into BJTs for the current amplification side of things.
I started designing with tubes when I was a kid. They were free and a
CK722 germanium transistor cost $7.
Same here. But over the decades I'd forgotten much about them. I
couldn't even recall whether grids had to be above or below cathode potential! I just want to do something a bit different. Been messing
around with semis for far too long; time to get back to my roots.
On Thu, 2 Oct 2025 14:20:59 +0100, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:
Cursitor Doom <cd@notformail.com> wrote:
On Thu, 2 Oct 2025 10:30:21 +0100, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:
Cursitor Doom <cd@notformail.com> wrote:
[...]
over the decades I'd forgotten much about them. I
couldn't even recall whether grids had to be above or below cathode
potential!
If the cathode glows but the grid doesn't, you have got it the right way >> >around.
If the cathodes are glowing I'd have done something wrong!
If they aren't, you've forgotten to switch it on.
You seem to be thinking of the heaters making it appear that the
cathodes are glowing.
My father had a copy of this.
I found it very interesting as soon as I could read. http://www.tubebooks.org/Books/Briggs_amplifiers.pdf
Edward Rawde <invalid@invalid.invalid> wrote:
[...]
My father had a copy of this.
I found it very interesting as soon as I could read.
http://www.tubebooks.org/Books/Briggs_amplifiers.pdf
From memory: Briggs's knowledge of valves (and circuits in general)
seemed to be based on hearsay and rule of thumb. The book might be entertaining and handy for a dabbler but it wasn't a good reference
source for someone who wanted to make reliable professional designs.
[Disclaimer: I read it a long time ago, so this was just the impression
I remember from it.]
On 10/6/2025 1:08 PM, Liz Tuddenham wrote:
Edward Rawde <invalid@invalid.invalid> wrote:
[...]
My father had a copy of this.
I found it very interesting as soon as I could read.
http://www.tubebooks.org/Books/Briggs_amplifiers.pdf
From memory: Briggs's knowledge of valves (and circuits in general)
seemed to be based on hearsay and rule of thumb. The book might be entertaining and handy for a dabbler but it wasn't a good reference
source for someone who wanted to make reliable professional designs.
Terman's books are good:
https://www.thriftbooks.com/w/radio-engineering/9518017/vintage/?vid=12651 90254&utm_source=google&utm_medium=cpc&utm_campaign=shopping_everything_el se_customer_acquisition_16970393167&utm_adgroup=&utm_term=&utm_content=593 719077582&gad_source=1&gad_campaignid=16970393167&gclid=EAIaIQobChMItfOIhK GQkAMV4GZHAR0SAxdoEAQYBiABEgJfEPD_BwE
and
ehsjr <ehsjr@verizon.net> wrote:
On 10/6/2025 1:08 PM, Liz Tuddenham wrote:https://www.thriftbooks.com/w/radio-engineers-handbook_frederick-emmons- >terman/18831137/item/26149366/?utm_source=google&utm_medium=cpc&utm_camp >aign=pmax_non_scarce_used_nca_22292660096&utm_adgroup=&utm_term=&utm_con >tent=&gad_source=1&gad_campaignid=22296401182&gclid=EAIaIQobChMItfOIhKGQ >kAMV4GZHAR0SAxdoEAQYAiABEgKSEvD_BwE#idiq=26149366&edition=12166618
Edward Rawde <invalid@invalid.invalid> wrote:
[...]
My father had a copy of this.
I found it very interesting as soon as I could read.
http://www.tubebooks.org/Books/Briggs_amplifiers.pdf
From memory: Briggs's knowledge of valves (and circuits in general)
seemed to be based on hearsay and rule of thumb. The book might be
entertaining and handy for a dabbler but it wasn't a good reference
source for someone who wanted to make reliable professional designs.
Terman's books are good:
https://www.thriftbooks.com/w/radio-engineering/9518017/vintage/?vid=12651 >> 90254&utm_source=google&utm_medium=cpc&utm_campaign=shopping_everything_el >> se_customer_acquisition_16970393167&utm_adgroup=&utm_term=&utm_content=593 >> 719077582&gad_source=1&gad_campaignid=16970393167&gclid=EAIaIQobChMItfOIhK >> GQkAMV4GZHAR0SAxdoEAQYBiABEgJfEPD_BwE
and
Terman is an excellentauthor, I bought a copy of "Radio Engineering"
many years.ago and still use it For really detailed theory I can
recommend "Electronic Designer's Handbook" by Landee, Davis & Albrecht -
but it certainly isn't for beginners.
ehsjr <ehsjr@verizon.net> wrote:
On 10/6/2025 1:08 PM, Liz Tuddenham wrote:https://www.thriftbooks.com/w/radio-engineers-handbook_frederick-emmons- terman/18831137/item/26149366/?utm_source=google&utm_medium=cpc&utm_camp aign=pmax_non_scarce_used_nca_22292660096&utm_adgroup=&utm_term=&utm_con tent=&gad_source=1&gad_campaignid=22296401182&gclid=EAIaIQobChMItfOIhKGQ kAMV4GZHAR0SAxdoEAQYAiABEgKSEvD_BwE#idiq=26149366&edition=12166618
Edward Rawde <invalid@invalid.invalid> wrote:
[...]
My father had a copy of this.
I found it very interesting as soon as I could read.
http://www.tubebooks.org/Books/Briggs_amplifiers.pdf
From memory: Briggs's knowledge of valves (and circuits in general)
seemed to be based on hearsay and rule of thumb. The book might be
entertaining and handy for a dabbler but it wasn't a good reference
source for someone who wanted to make reliable professional designs.
Terman's books are good:
https://www.thriftbooks.com/w/radio-engineering/9518017/vintage/?vid=12651 >> 90254&utm_source=google&utm_medium=cpc&utm_campaign=shopping_everything_el >> se_customer_acquisition_16970393167&utm_adgroup=&utm_term=&utm_content=593 >> 719077582&gad_source=1&gad_campaignid=16970393167&gclid=EAIaIQobChMItfOIhK >> GQkAMV4GZHAR0SAxdoEAQYBiABEgJfEPD_BwE
and
Terman is an excellentauthor, I bought a copy of "Radio Engineering"
many years.ago and still use it For really detailed theory I can
recommend "Electronic Designer's Handbook" by Landee, Davis & Albrecht -
but it certainly isn't for beginners.
Edward Rawde <invalid@invalid.invalid> wrote:
[...]
My father had a copy of this.
I found it very interesting as soon as I could read.
http://www.tubebooks.org/Books/Briggs_amplifiers.pdf
From memory: Briggs's knowledge of valves (and circuits in general)
seemed to be based on hearsay and rule of thumb. The book might be entertaining and handy for a dabbler but it wasn't a good reference
source for someone who wanted to make reliable professional designs.
[Disclaimer: I read it a long time ago, so this was just the impression
I remember from it.]
--
~ Liz Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk
Cursitor Doom <cd@notformail.com> wrote:
On Thu, 2 Oct 2025 14:20:59 +0100, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:
Cursitor Doom <cd@notformail.com> wrote:
On Thu, 2 Oct 2025 10:30:21 +0100, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:
Cursitor Doom <cd@notformail.com> wrote:
[...]
over the decades I'd forgotten much about them. I
couldn't even recall whether grids had to be above or below cathode
potential!
If the cathode glows but the grid doesn't, you have got it the right way >> >> >around.
If the cathodes are glowing I'd have done something wrong!
If they aren't, you've forgotten to switch it on.
You seem to be thinking of the heaters making it appear that the
cathodes are glowing.
The heaters generally glow brighter than the cathodes but if the cathode >isn't glowing at dull-red temperature, it won't emit properly.
On Mon, 6 Oct 2025 13:35:18 +0100, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:
Cursitor Doom <cd@notformail.com> wrote:
On Thu, 2 Oct 2025 14:20:59 +0100, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:
Cursitor Doom <cd@notformail.com> wrote:
On Thu, 2 Oct 2025 10:30:21 +0100, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:
Cursitor Doom <cd@notformail.com> wrote:
[...] > over the decades I'd forgotten much about them. I >
couldn't even recall whether grids had to be above or below cathode
potential!
If the cathode glows but the grid doesn't, you have got it the
right way around.
If the cathodes are glowing I'd have done something wrong!
If they aren't, you've forgotten to switch it on.
You seem to be thinking of the heaters making it appear that the
cathodes are glowing.
The heaters generally glow brighter than the cathodes but if the cathode >isn't glowing at dull-red temperature, it won't emit properly.
How would one even notice a "dull-red temperature"?
Cursitor Doom <cd@notformail.com> wrote:
On Mon, 6 Oct 2025 13:35:18 +0100, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:
Cursitor Doom <cd@notformail.com> wrote:
On Thu, 2 Oct 2025 14:20:59 +0100, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:
Cursitor Doom <cd@notformail.com> wrote:
On Thu, 2 Oct 2025 10:30:21 +0100, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:
Cursitor Doom <cd@notformail.com> wrote:
[...] > over the decades I'd forgotten much about them. I >
couldn't even recall whether grids had to be above or below cathode >> >> >> >> potential!
If the cathode glows but the grid doesn't, you have got it the
right way around.
If the cathodes are glowing I'd have done something wrong!
If they aren't, you've forgotten to switch it on.
You seem to be thinking of the heaters making it appear that the
cathodes are glowing.
The heaters generally glow brighter than the cathodes but if the cathode
isn't glowing at dull-red temperature, it won't emit properly.
How would one even notice a "dull-red temperature"?
It glows in the dark.
On Thu, 02 Oct 2025 09:53:42 -0700, john larkin <jl@glen--canyon.com>
wrote:
On Thu, 02 Oct 2025 12:59:25 +0100, Cursitor Doom <cd@notformail.com>
wrote:
On Wed, 01 Oct 2025 16:49:21 -0700, john larkin <jl@glen--canyon.com>
wrote:
On Thu, 02 Oct 2025 00:05:19 +0100, Cursitor Doom <cd@notformail.com>
wrote:
On Wed, 01 Oct 2025 10:39:09 -0700, john larkin <jl@glen--canyon.com> >>>>> wrote:
On Wed, 01 Oct 2025 18:07:42 +0100, Cursitor Doom <cd@notformail.com> >>>>>> wrote:
On Wed, 01 Oct 2025 07:23:46 -0700, john larkin <jl@glen--canyon.com> >>>>>>> wrote:
On Wed, 01 Oct 2025 14:19:14 +0100, Cursitor Doom <cd@notformail.com> >>>>>>>> wrote:
On Mon, 29 Sep 2025 09:42:39 -0700, john larkin <jl@glen--canyon.com> >>>>>>>>> wrote:
On Sun, 28 Sep 2025 22:50:51 +0100, Cursitor Doom <cd@notformail.com>
wrote:
On Sun, 28 Sep 2025 10:09:34 -0700, john larkin <jl@glen--canyon.com>
wrote:
On Sun, 28 Sep 2025 17:38:40 +0100, Cursitor Doom <cd@notformail.com>
wrote:
On Sun, 28 Sep 2025 08:16:10 -0700, john larkin <jl@glen--canyon.com>
wrote:
On Sun, 28 Sep 2025 09:04:52 +0100, Cursitor Doom <cd@notformail.com>
wrote:
On Sat, 27 Sep 2025 09:10:29 -0700, john larkin <jl@glen--canyon.com>
wrote:
https://www.timeout.com/travel/coolest-neighbourhoods-in-the-world-2025
Two things I noticed is how many places have hideous overhead wires,
and how much signage is in English.
I lived in Berlin for some years in a delightful Kietz very similar to
number 1 on this list: antiquarian booksellers on every street. Some
really fascinating titles got published pre-1900; stuff that would
never see the light of day now.
I modestly note that my little niche is #35 on the list. My little lab
is a two minute walk from GPS, which is an authentic old dive bar.
I've heard this term 'dive bar' before in popular songs. What exactly
is that? I'm guessing some seedy joint where felonious types play >>>>>>>>>>>>> pool?
It's an old neighborhood bar that smells like an old neighborhood bar,
partonized by locals and worker-guys. It might have a pool table or a
fireplace. It has a few good but not fancy beers on tap. >>>>>>>>>>>>
The pizza place close by makes deliveries to your table at GPS. People
hate to let eating interfere with their drinking.
I asked the bar lady "Do you have any good rum, like Ron Zacapa?" and
she said "This ain't that kind of joint, honey."
Classic Americana. :-D
The Glen Park library is were they busted the Silk Road guy. A few
blocks away is (or emphatically was) the first dynamite factory in the
USA.
Oh dear! Go *bang* did it?
Yes. It lasted almost two years. They rebuilt it a couple miles to the
west, and that lasted two more.
https://www.dropbox.com/scl/fi/hi1j889kkn465fgpx5xgk/Glen_Canyon_Dynamite.jpg?rlkey=uq333s2okih26zgpicvcy7fb0&raw=1
Very quiet here today. Not even any of the regular trolls around. >>>>>>>>>>>>
Not much electronics here lately.
I need a small circuit to make +20 volts into -20 at maybe 400 mA. >>>>>>>>>>>> There are lots of ways to do that.
I need to make 250VDC @ 150mA from 240VAC Gotta be low noise. Any >>>>>>>>>>> suggestions?
There's not much in the way of commercial supplies in that range, and
nothing affordable.
I'd have thought *someone* must have such a supply, but as you say, >>>>>>>>> not much around.
A transformer+rectifier+filter should be OK.
What - you mean an isolation transformer or something with more >>>>>>>>> secodary turns?
Something like that.
What's the load going to be?
Plate voltages for 4x ECC83 toobs. They will run at above and below >>>>>>>>> 250VDC, but it does change all sorts of parameters if they're tasked >>>>>>>>> to do that, so I'd prefer to stick to 250 for the sake of simplicity >>>>>>>>> and saves having to extrapolate from published data.
Tubes are wildly variant. The data sheets are just sorta
approximations, so I wouldn't sweat a few volts.
Tubes vary so much that people used to sell matched pairs. That was >>>>>> before negative feedback was invented.
BJTs are notorious for that, too. And people also selected matched
pairs of those for the same reason.
So you don't need regulation, and you can RC filter for the supply to >>>>>>>> early single-ended stages.
Sounds like a classic toob amp. Do what they did.
That is exactly what I'm not going to do, John. This may shock you, >>>>>>> but for the first time in 30 years on this group, I've decided to >>>>>>> actually *design* something!
Ack! That's unprecidented here.
Certainly is in my case! :-)
There's a first time for everything, they
say, and God knows I've been told enough times over the years to go >>>>>>> design something for a change. Well that time has finally come. I've >>>>>>> been spending 99% of my time fixing up old vintage test equipment and >>>>>>> I fancy a change. And let's be honest: it's well overdue. Wish me >>>>>>> luck! :-)
Yes. Let me know if I can help. We have a lot of parts in stock, but >>>>>> no tubes or octal sockets or cloth-covered wire or like that.
I have the tubes. The sockets: some I have, some I'll need to order. I >>>>> was planning to make it all-tube, but difficulty in finding decent
quality output transformers of the right spec put paid to that. So now >>>>> it's to be a hybrid: tube front end going into BJTs for the current
amplification side of things.
Or mosfets.
Well, I'm aware Mosfets are used for certain exotic amplifier modes
(can't recall exactly which but might be class D or G or something)
but I'm going full traditional here with class A or AB perhaps. And
you can't use Mosfets for that AFAICS. But sure, if you're going to
chop up the signal and mess around with it, Mosfets are ideal.
Mosfets can work fine in linear amps, but you've got to be careful
about their safe operating area. A lot of fets are optimized for fast
switching. We test them to be safe.
https://www.dropbox.com/scl/fi/oq1bgzkpsdcsmrg63w1r9/ExFets.jpg?rlkey=jcscvg5vt1qebgyxb0gt5575q&dl=0
We use one mosfet that's rated for 1000 amps and 1000 watts.
If you hang an opamp on a mosfet, it becomes ultra-linear.
Let's see if I understand you right. Mosfets are typically switches,
so to control that sharp on/off region, you need some tight feedback
loop to manage it as an amplifier? I'd never thought of that TBH!
On Thu, 02 Oct 2025 09:53:42 -0700, john larkin <jl@glen--canyon.com>
wrote:
On Thu, 02 Oct 2025 12:59:25 +0100, Cursitor Doom <cd@notformail.com> >>wrote:
On Wed, 01 Oct 2025 16:49:21 -0700, john larkin <jl@glen--canyon.com> >>>wrote:
On Thu, 02 Oct 2025 00:05:19 +0100, Cursitor Doom <cd@notformail.com> >>>>wrote:
On Wed, 01 Oct 2025 10:39:09 -0700, john larkin <jl@glen--canyon.com> >>>>>wrote:
On Wed, 01 Oct 2025 18:07:42 +0100, Cursitor Doom <cd@notformail.com> >>>>>>wrote:
On Wed, 01 Oct 2025 07:23:46 -0700, john larkin <jl@glen--canyon.com> >>>>>>>wrote:
On Wed, 01 Oct 2025 14:19:14 +0100, Cursitor Doom <cd@notformail.com> >>>>>>>>wrote:
On Mon, 29 Sep 2025 09:42:39 -0700, john larkin <jl@glen--canyon.com> >>>>>>>>>wrote:
On Sun, 28 Sep 2025 22:50:51 +0100, Cursitor Doom <cd@notformail.com> >>>>>>>>>>wrote:
On Sun, 28 Sep 2025 10:09:34 -0700, john larkin <jl@glen--canyon.com>
wrote:
On Sun, 28 Sep 2025 17:38:40 +0100, Cursitor Doom <cd@notformail.com>
wrote:
On Sun, 28 Sep 2025 08:16:10 -0700, john larkin <jl@glen--canyon.com>
wrote:
On Sun, 28 Sep 2025 09:04:52 +0100, Cursitor Doom <cd@notformail.com>
wrote:
On Sat, 27 Sep 2025 09:10:29 -0700, john larkin <jl@glen--canyon.com>
wrote:
https://www.timeout.com/travel/coolest-neighbourhoods-in-the-world-2025
Two things I noticed is how many places have hideous overhead wires,
and how much signage is in English.
I lived in Berlin for some years in a delightful Kietz very similar to
number 1 on this list: antiquarian booksellers on every street. Some
really fascinating titles got published pre-1900; stuff that would
never see the light of day now.
I modestly note that my little niche is #35 on the list. My little lab
is a two minute walk from GPS, which is an authentic old dive bar.
I've heard this term 'dive bar' before in popular songs. What exactly
is that? I'm guessing some seedy joint where felonious types play >>>>>>>>>>>>>pool?
It's an old neighborhood bar that smells like an old neighborhood bar,
partonized by locals and worker-guys. It might have a pool table or a
fireplace. It has a few good but not fancy beers on tap. >>>>>>>>>>>>
The pizza place close by makes deliveries to your table at GPS. People
hate to let eating interfere with their drinking.
I asked the bar lady "Do you have any good rum, like Ron Zacapa?" and
she said "This ain't that kind of joint, honey."
Classic Americana. :-D
The Glen Park library is were they busted the Silk Road guy. A few
blocks away is (or emphatically was) the first dynamite factory in the
USA.
Oh dear! Go *bang* did it?
Yes. It lasted almost two years. They rebuilt it a couple miles to the
west, and that lasted two more.
https://www.dropbox.com/scl/fi/hi1j889kkn465fgpx5xgk/Glen_Canyon_Dynamite.jpg?rlkey=uq333s2okih26zgpicvcy7fb0&raw=1
Very quiet here today. Not even any of the regular trolls around. >>>>>>>>>>>>
Not much electronics here lately.
I need a small circuit to make +20 volts into -20 at maybe 400 mA. >>>>>>>>>>>>There are lots of ways to do that.
I need to make 250VDC @ 150mA from 240VAC Gotta be low noise. Any >>>>>>>>>>>suggestions?
There's not much in the way of commercial supplies in that range, and >>>>>>>>>>nothing affordable.
I'd have thought *someone* must have such a supply, but as you say, >>>>>>>>>not much around.
A transformer+rectifier+filter should be OK.
What - you mean an isolation transformer or something with more >>>>>>>>>secodary turns?
Something like that.
What's the load going to be?
Plate voltages for 4x ECC83 toobs. They will run at above and below >>>>>>>>>250VDC, but it does change all sorts of parameters if they're tasked >>>>>>>>>to do that, so I'd prefer to stick to 250 for the sake of simplicity >>>>>>>>>and saves having to extrapolate from published data.
Tubes are wildly variant. The data sheets are just sorta >>>>>>approximations, so I wouldn't sweat a few volts.
Tubes vary so much that people used to sell matched pairs. That was >>>>>>before negative feedback was invented.
BJTs are notorious for that, too. And people also selected matched >>>>>pairs of those for the same reason.
So you don't need regulation, and you can RC filter for the supply to >>>>>>>>early single-ended stages.
Sounds like a classic toob amp. Do what they did.
That is exactly what I'm not going to do, John. This may shock you, >>>>>>>but for the first time in 30 years on this group, I've decided to >>>>>>>actually *design* something!
Ack! That's unprecidented here.
Certainly is in my case! :-)
There's a first time for everything, they
say, and God knows I've been told enough times over the years to go >>>>>>>design something for a change. Well that time has finally come. I've >>>>>>>been spending 99% of my time fixing up old vintage test equipment and >>>>>>>I fancy a change. And let's be honest: it's well overdue. Wish me >>>>>>>luck! :-)
Yes. Let me know if I can help. We have a lot of parts in stock, but >>>>>>no tubes or octal sockets or cloth-covered wire or like that.
I have the tubes. The sockets: some I have, some I'll need to order. I >>>>>was planning to make it all-tube, but difficulty in finding decent >>>>>quality output transformers of the right spec put paid to that. So now >>>>>it's to be a hybrid: tube front end going into BJTs for the current >>>>>amplification side of things.
Or mosfets.
Well, I'm aware Mosfets are used for certain exotic amplifier modes >>>(can't recall exactly which but might be class D or G or something)
but I'm going full traditional here with class A or AB perhaps. And
you can't use Mosfets for that AFAICS. But sure, if you're going to
chop up the signal and mess around with it, Mosfets are ideal.
Mosfets can work fine in linear amps, but you've got to be careful
about their safe operating area. A lot of fets are optimized for fast >>switching. We test them to be safe.
https://www.dropbox.com/scl/fi/oq1bgzkpsdcsmrg63w1r9/ExFets.jpg?rlkey=jcscvg5vt1qebgyxb0gt5575q&dl=0
We use one mosfet that's rated for 1000 amps and 1000 watts.
If you hang an opamp on a mosfet, it becomes ultra-linear.
Let's see if I understand you right. Mosfets are typically switches,
so to control that sharp on/off region, you need some tight feedback
loop to manage it as an amplifier? I'd never thought of that TBH!
https://www.timeout.com/travel/coolest-neighbourhoods-in-the-world-2025
Two things I noticed is how many places have hideous overhead wires,
and how much signage is in English.
Joerg <news@analogconsultants.com>wrote:
On 9/27/25 9:10 AM, john larkin wrote:
https://www.timeout.com/travel/coolest-neighbourhoods-in-the-world-2025
Two things I noticed is how many places have hideous overhead wires,
and how much signage is in English.
And they are usually terribly crowded. Why do people want to feel like >sardines in a can? To me the coolest places are right here where we live:
https://www.analogconsultants.com/ng/bike/SouthFork1.JPG
You can only get there by mountain bike, by kayak or on foot. On foot it >takes a lot of hours. Mountain biking there isn't for the faint of
heart. Even an experienced rider turfed it on the way out there.
My MTB has panniers and I brought homebrew IPA plus Dixie cups so we
hung out there for a while when I took that picture. The plop of a
Grolsch bottle echoing back from the valleys is a heavenly sound :-)
On 9/27/25 9:10 AM, john larkin wrote:
https://www.timeout.com/travel/coolest-neighbourhoods-in-the-world-2025
Two things I noticed is how many places have hideous overhead wires,
and how much signage is in English.
And they are usually terribly crowded. Why do people want to feel like >sardines in a can? To me the coolest places are right here where we live:
https://www.analogconsultants.com/ng/bike/SouthFork1.JPG
You can only get there by mountain bike, by kayak or on foot. On foot it >takes a lot of hours. Mountain biking there isn't for the faint of
heart. Even an experienced rider turfed it on the way out there.
My MTB has panniers and I brought homebrew IPA plus Dixie cups so we
hung out there for a while when I took that picture. The plop of a
Grolsch bottle echoing back from the valleys is a heavenly sound :-)
On 9/27/25 9:10 AM, john larkin wrote:
https://www.timeout.com/travel/coolest-neighbourhoods-in-the-world-2025
Two things I noticed is how many places have hideous overhead wires,
and how much signage is in English.
And they are usually terribly crowded. Why do people want to feel like sardines in a can? To me the coolest places are right here where we live:
https://www.analogconsultants.com/ng/bike/SouthFork1.JPG
You can only get there by mountain bike, by kayak or on foot. On foot it takes a lot of hours. Mountain biking there isn't for the faint of
heart. Even an experienced rider turfed it on the way out there.
My MTB has panniers and I brought homebrew IPA plus Dixie cups so we
hung out there for a while when I took that picture. The plop of a
Grolsch bottle echoing back from the valleys is a heavenly sound :-)
